Fifty-seven-year-old Michael Selsor is set to be executed by lethal injection on Tuesday at the Oklahoma State Penitentiary in McAlester.

Selsor was twice convicted of first-degree murder and sentenced to die for the 1975 shooting death of 55-year-old Clayton Chandler. Chandler was shot eight times during an armed robbery that netted the thieves a little more than $500.

The state Pardon and Parole Board voted 4-1 against commuting Selsor's death sentence to life in prison without the possibility of parole. The U.S. Supreme Court denied his request for a stay on Friday.